Lens driving device

ABSTRACT

A lens driving device is provided, including a frame, a lens holder, a spring sheet, and at least one damping element. The lens holder is movably disposed in the frame. The spring sheet has an outer periphery portion combined with the frame, an inner periphery portion combined with the lens holder, and an arm portion connected between the outer periphery portion and the inner periphery portion. The damping element is connected between the arm portion of the spring sheet and at least one of the frame and the lens holder.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority of Taiwan Patent Application No.104140047, filed on Dec. 1, 2015, the entirety of which is incorporatedby reference herein.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a lens driving device, and in particular to alens driving device which requires less focusing time.

Description of the Related Art

Many mobile devices such as mobile phones are equipped with digitalcameras as a basic requirement nowadays, and this is only possiblethanks to the miniaturization of lens driving devices. In order toprovide automatic focusing or zooming, a commonly used miniature lensdriving device is a Voice Coil Motor (VCM), which carries a lens and canmove the lens back and forth along an image-capturing optical axis bymeans of a coil, a magnet, and a spring sheet.

Generally, when a lens (of VCM) is moved to a fixed position to bringthe subject into focus, it may shake for a period, and then is slowlyreaches a steady state. This time required (for the lens) to move to thestop from being at rest is called the Dynamic Response Time, whichaffects the length of the focusing time of the lens driving device (Thelonger the Dynamic Response Time, the longer the focusing time. Thisadversely affects the effectiveness of the lens driving device).Therefore, how to shorten the Dynamic Response Time to reduce thefocusing time of the lens driving device deserves careful consideration.

BRIEF SUMMARY OF THE INVENTION

An object of the invention is to provide a lens driving device which canreduce the shake generated by focusing the lens, so that the DynamicResponse Time and hence the focusing time can be shortened.

An embodiment of the invention provides a lens driving device, includinga frame, a lens holder, a spring sheet, and at least one dampingelement. The lens holder is movably disposed in the frame. The springsheet has an outer periphery portion, an inner periphery portion, and atleast one arm portion. The outer periphery portion is combined with theframe, the inner periphery portion is combined with the lens holder, andthe arm portion is connected between the outer periphery portion and theinner periphery portion. The damping element is connected between thearm portion of the spring sheet and at least one of the frame and lensholder.

In some embodiments, the arm portion of the spring sheet forms at leastone protrusion that extends toward the frame, and the frame forms atleast one recess corresponding to the protrusion, wherein the dampingelement is connected between the protrusion and the recess.

In some embodiments, the arm portion of the spring sheet forms at leastone protrusion that extends toward the lens holder, and the lens holderforms at least one recess corresponding to the protrusion, wherein thedamping element is connected between the protrusion and the recess.

In some embodiments, the frame forms at least one connected portion thatprotrudes from an inner side thereof, and the damping element isconnected between the arm portion of the spring sheet and the connectedportion.

In some embodiments, the inner periphery portion of the spring sheetforms at least one opening to which a part of a connected surface of thelens holder is exposed, and the damping element is connected between thearm portion of the spring sheet, the opening, and the exposed part ofthe connected surface of the lens holder.

In some embodiments, the damping element is connected to the arm portionof the spring sheet in a winding manner.

In some embodiments, the damping element is a soft gel.

In some embodiments, the damping element, the frame, and the lens holdercomprise the same resin material.

In some embodiments, the frame and the spring sheet are respectively atop casing and an upper spring sheet of the lens driving device.

In some embodiments, the frame and the spring sheet are respectively abottom base and a lower spring sheet of the lens driving device.

In order to illustrate the purposes, features, and advantages of theinvention, the preferred embodiments and drawings of the invention areshown in detail as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 is an exploded view of a lens driving device in accordance withan embodiment of the invention;

FIG. 2 is a schematic view of the lens driving device in FIG. 1 afterassembly;

FIG. 3A is a schematic plane view illustrating the configuration of thespring sheet, damping elements, and frame of a lens driving device inaccordance with an embodiment of the invention, and FIG. 3B is anenlarged perspective view of part A of FIG. 3A;

FIG. 4 is a schematic cross-sectional view illustrating the connectionbetween the spring sheet and damping element in accordance with anotherembodiment of the invention;

FIG. 5A is a schematic plane view illustrating the configuration of thespring sheet, damping elements, and frame of a lens driving device inaccordance with another embodiment of the invention, and FIG. 5B is anenlarged perspective view of part B of FIG. 5A;

FIG. 6A is a schematic plane view illustrating the configuration of thespring sheet, damping elements, and lens holder of a lens driving devicein accordance with another embodiment of the invention, and FIG. 6B isan enlarged perspective view of part C of FIG. 6A;

FIG. 7A is a schematic plane view illustrating the configuration of thespring sheet, damping elements, and lens holder of a lens driving devicein accordance with another embodiment of the invention, and FIG. 7B isan enlarged perspective view of part D of FIG. 7A;

FIG. 8A is a schematic plane view illustrating the configuration of thespring sheet, damping elements, and frame of a lens driving device inaccordance with another embodiment of the invention, and FIG. 8B is anenlarged perspective view of part E of FIG. 8A; and

FIG. 9A is a schematic plane view illustrating the configuration of thespring sheet, damping elements, and lens holder of a lens driving devicein accordance with another embodiment of the invention, and FIG. 9B isan enlarged perspective view of part F of FIG. 9A.

DETAILED DESCRIPTION OF THE INVENTION

A detailed description is given in the following embodiments withreference to the accompanying drawings.

In the following detailed description, the orientations of “on”,“above”, “under”, and “below” are used for representing the relationshipbetween the relative positions of each element as illustrated in thedrawings, and are not meant to limit the invention.

In addition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed. Variousfeatures may be arbitrarily drawn in different scales for the sake ofsimplicity and clarity. Furthermore, some elements not shown ordescribed in the embodiments have the forms known by persons skilled inthe field of the invention.

Please refer to FIG. 1 and FIG. 2, wherein FIG. 1 is an exploded view ofa lens driving device 1 in accordance with an embodiment of theinvention, and FIG. 2 is a schematic view of the lens driving device 1after assembly. The lens driving device 1 may be a Voice Coil Motor(VCM), which defines three axial directions that are perpendicular toeach other, namely an X-axis direction, a Y-axis direction, and a Z-axisdirection, and includes a lens (not shown) therein, wherein the lensdefines an image-capturing optical axis O which is substantiallyparallel to the Z-axis.

As shown in FIG. 1 and FIG. 2, the lens driving device 1 includes a topcasing 10, a bottom base 20, a lens holder 30, a coil 40, a plurality of(e.g. four) magnets 50, an upper spring sheet 60, and a lower springsheet 70.

In this embodiment, the top casing 10 is a hollow structure and can becombined with the bottom base 20 to form a receiving space, forreceiving and protecting other parts of the lens driving device 1 asdescribed above. Also, the top casing 10 has an opening 12 through whichthe lens (not shown) in the lens driving device 1 can capture light fromthe outside. The lens holder 30 is a hollow ring structure having asubstantially octangular periphery and has a through hole 32, whereinthe through hole 32 forms a thread structure 322 corresponding toanother thread structure on the lens, such that the lens can be lockedin the through hole 32. The coil 40 is wound around the periphery of thelens holder 30. The magnets 50 may be permanent magnets and are fixed atthe four respective corners of the bottom base 20 and correspond to thecoil 40. By varying the current input into the coil 40, differentmagnetic fields are generated between the coil 40 and the magnets 50 todrive the lens holder 30 and the lens therein back and forth along theimage-capturing optical axis O, so that focusing or zooming is carriedout

It should be realized that the lens holder 30 is movably disposed in thereceiving space formed by the top casing 10 and the bottom base 20 (thetop casing 10 and the bottom base 20 form the frame of the lens drivingdevice 1), and is elastically clamped by the movable inner peripheryportions of the upper spring sheet 60 and the lower spring sheet 70.Accordingly, the upper and lower spring sheets 60 and 70 can limit therange in which the lens holder 30 can be moved and provide the buffercapacity for the displacement of the lens holder 30 along the X-axis,the Y-axis, and the Z-axis.

However, the above design (i.e. the lens holder 30 being clamped by theupper and lower spring sheets 60 and 70 which are flexible and thinsheet structure) also results in vibration/shake of the lens holder 30and the lens therein when it is moved to a fixed position to bring thesubject into focus, so that the Dynamic Response Time is extended.Therefore, the following further describes damping elements are used invarious embodiments (with reference to FIGS. 3 to 9) of the invention soas to absorb and inhibit the shake generated by focusing the lens,thereby shortening the Dynamic Response Time and the focusing time andfurther improving the effectiveness of the lens driving device 1.

Please refer to FIG. 3A and FIG. 3B, wherein FIG. 3A is a schematicplane view illustrating the configuration of the spring sheet 60,damping elements 80, and frame 10 of a lens driving device in accordancewith an embodiment of the invention, and FIG. 3B is an enlargedperspective view of part A of FIG. 3A. It should be realized that theupper spring sheet 60 and the top casing 10 of the lens driving device 1are used as examples for illustration in this embodiment, but the upperspring sheet 60 and the top casing 10 may also be replaced by the lowerspring sheet 70 and the bottom base 20 of the lens driving device 1(FIG. 1).

As shown in FIG. 3A and FIG. 3B, the spring sheet 60 includes an outerperiphery portion 62 having a substantially rectangular shape, an innerperiphery portion 64 having a substantially annular shape, and aplurality of (e.g. four) elongated arm portions 66 connected between theouter periphery portion 62 and the inner periphery portion 64. The outerperiphery portion 62 is configured to be combined with the four cornersof the top casing 10 (the frame) by, for example, adhesive. The innerperiphery portion 64 is configured to be combined with the lens holder30 by, for example, adhesive. The four arm portions 66 extend betweenthe outer periphery portion 62 and the inner periphery portion 64 andare symmetrical to each other with equal intervals, so as to increasethe buffer capacity for the displacement of the lens holder 30 along theX-axis, the Y-axis, and the Z-axis.

Moreover, a plurality of (e.g. four) damping elements 80 can be disposedbetween the arm portions 66 of the spring sheet 60 and (the four cornersof) the adjacent frame 10, wherein the damping elements 80 are coupledto the arm portions 66 and to the frame 10 (FIG. 3B), so that thedamping elements 80 can absorb and inhibit the shake generated by thearm portions 66 of the spring sheet 60 when the lens is moved to a fixedposition to bring the subject into focus. Therefore, the DynamicResponse Time and the focusing time are effectively shortened.

The damping elements 80 may be soft gel or any other applicable dampingmaterial. Also, the frame 10, preferably, may comprise resin material,so that a better bonding strength can be achieved between the dampingelements 80 and the frame 10, thereby preventing the damping elements 80from easily separating from the frame 10.

FIG. 4 is a schematic cross-sectional view illustrating the connectionbetween the spring sheet 60 and damping element 80 in accordance withanother embodiment of the invention. As shown in FIG. 4, the dampingelement 80 can also be connected to the arm portion 66 of the springsheet 60 in a winding manner. Thus, the bonding strength between thedamping elements 80 and the metal spring sheet 60 can also be improved,thereby preventing the damping elements 80 from easily separating fromthe spring sheet 60.

Please refer to FIG. 5A and FIG. 5B, wherein FIG. 5A is a schematicplane view illustrating the configuration of the spring sheet 60,damping elements 80, and frame 10 of a lens driving device in accordancewith another embodiment of the invention, and FIG. 5B is an enlargedperspective view of part B of FIG. 5A. Note that this embodiment (FIGS.5A and 5B) differs from the embodiment of FIGS. 3A and 3B in that thearm portions 66 of the spring sheet 60 further form a plurality of (e.g.four) protrusions 66A that extend toward the frame 10 and correspond tothe four corners of the frame 10. Also, the frame 10 further forms aplurality of recesses 14 (FIG. 5B) corresponding to the protrusions 66A.Accordingly, the damping elements 80 can be connected between theprotrusions 66A of the arm portions 66 and the recesses 14 of the frame10 (in this embodiment, the damping elements 80 are coupled to theprotrusions 66A and to the recesses 14, and parts of the dampingelements 80 will flow into the gaps between the lower surfaces of theprotrusions 66A and the recesses 14), so that the damping elements 80can absorb and inhibit the shake generated by the arm portions 66 of thespring sheet 60 when the lens is moved to a fixed position to bring thesubject into focus, thereby effectively shortening the Dynamic ResponseTime and the focusing time.

Moreover, the recesses 14 of this embodiment each are designed to have atriangular shape (but the invention is not limited thereto), and thedamping element 80 correspondingly covers the entire triangular recess14. Thus, the bonding strength between the damping elements 80 and theframe 10 can be increased, and the bonding strength between theprotrusions 66A of the arm portions 66 and the frame 10 can also beincreased. Furthermore, with the design of the recesses 14, the dampingelements 80 can be accurately adhered to and positioned in the desiredpositions, and the use amount of damping elements 80 is reduced.

Please refer to FIG. 6A and FIG. 6B, wherein FIG. 6A is a schematicplane view illustrating the configuration of the spring sheet 60,damping elements 80, and lens holder 30 of a lens driving device inaccordance with another embodiment of the invention, and FIG. 6B is anenlarged perspective view of part C of FIG. 6A. Note that thisembodiment (FIGS. 6A and 6B) differs from the embodiment of FIGS. 3A and3B in that the plurality of damping elements 80 are disposed between thearm portions 66 of the spring sheet 60 and the lens holder 30, whereinthe damping elements 80 are coupled to the arm portions 66 and to thelens holder 30 (FIG. 6B), so that the damping elements 80 can absorb andinhibit the shake generated by the arm portions 66 of the spring sheet60 when the lens is moved to a fixed position to bring the subject intofocus, thereby effectively shortening the Dynamic Response Time and thefocusing time.

In this embodiment, the damping elements 80 may be soft gel or any otherapplicable damping material. Also, the lens holder 30, preferably, maycomprise resin material, so that a better bonding strength can beachieved between the damping elements 80 and the lens holder 30, therebypreventing the damping elements 80 from easily separating from the lensholder 30. In some embodiments, the damping element 80 can also beconnected to the arm portion 66 of the spring sheet 60 in a windingmanner. Thus, the bonding strength between the damping elements 80 andthe metal spring sheet 60 can also be improved, thereby preventing thedamping elements 80 from easily separating from the spring sheet 60.

Please refer to FIG. 7A and FIG. 7B, wherein FIG. 7A is a schematicplane view illustrating the configuration of the spring sheet 60,damping elements 80, and lens holder 30 of a lens driving device inaccordance with another embodiment of the invention, and FIG. 7B is anenlarged perspective view of part D of FIG. 7A. Note that thisembodiment (FIGS. 7A and 7B) differs from the embodiment of FIGS. 6A and6B in that the arm portions 66 of the spring sheet 60 further form aplurality of (e.g. four) protrusions 66B that extend toward the lensholder 30, and the lens holder 30 further forms a plurality of recesses34 (FIG. 7B) corresponding to the protrusions 66B. Accordingly, thedamping elements 80 can be connected between the protrusions 66B of thearm portions 66 and the recesses 34 of the lens holder 30 (in thisembodiment, the damping elements 80 are coupled to the protrusions 66Band to the recesses 34, and parts of the damping elements 80 will flowinto the gaps between the lower surfaces of the protrusions 66B and therecesses 34), so that the damping elements 80 can absorb and inhibit theshake generated by the arm portions 66 of the spring sheet 60 when thelens is moved to a fixed position to bring the subject into focus,thereby effectively shortening the Dynamic Response Time and thefocusing time.

Moreover, the recesses 34 of this embodiment each are designed to have asemicircular shape (but the invention is not limited thereto), and thedamping element 80 correspondingly covers the entire semicircular recess34. Thus, the bonding strength between the damping elements 80 and thelens holder 30 can be increased, and the bonding strength between theprotrusions 66B of the arm portions 66 and the lens holder 30 can alsobe increased. Furthermore, with the design of the recesses 34, thedamping elements 80 can be accurately adhered to and positioned in thedesired positions and the use amount of damping elements 80 is reduced.

Please refer to FIG. 8A and FIG. 8B, wherein FIG. 8A is a schematicplane view illustrating the configuration of the spring sheet 70,damping elements 80, and frame 20 of a lens driving device in accordancewith another embodiment of the invention, and FIG. 8B is an enlargedperspective view of part E of FIG. 8A. It should be realized that thelower spring sheet 70 and the bottom base 20 of the lens driving device1 are used as examples for illustration in this embodiment, but thelower spring sheet 70 and the bottom base 20 may also be replaced by theupper spring sheet 60 and the top casing 10 of the lens driving device 1(FIG. 1).

As shown in FIG. 8A and FIG. 8B, the spring sheet 70 also includes anouter periphery portion 72 configured to be combined with the bottombase 20 (the frame), an inner periphery portion 74 configured to becombined with the lens holder 30 (not shown), and a plurality of (e.g.four) elongated arm portions 76 connected between the outer peripheryportion 72 and the inner periphery portion 74.

Moreover, the four sidewalls of the bottom base 20 further respectivelyform a connected portion 22 (FIG. 8B) that protrudes from the inner sidethereof, and the corresponding arm portion 76 of the spring sheet 70 canbe disposed on a side (e.g. the upper side) of the connected portion 22.Also, a plurality of damping elements 80 can be disposed between the armportions 76 of the spring sheet 70 and the adjacent connected portions22. More specifically, the damping elements 80 are adhered to theconnected portions 22 and the inner sidewalls of the bottom base 20 andare connected to the arm portions 76 of the spring sheet 70 in a windingmanner (it should be noted that the damping elements 80 each are atleast connected to two opposite surfaces and another surface between thetwo surfaces of the corresponding arm portion 76), so that the dampingelements 80 can absorb and inhibit the shake generated by the armportions 76 of the spring sheet 70 when the lens is moved to a fixedposition to bring the subject into focus, thereby effectively shorteningthe Dynamic Response Time and the focusing time. Furthermore, with thedesign of connected portions 22, the damping elements 80 can beaccurately adhered to and positioned in the desired positions.

In this embodiment, the damping elements 80 may be soft gel or any otherapplicable damping material. Also, the bottom base 20 (the frame),preferably, may comprise resin material, so that a better bondingstrength can be achieved between the damping elements 80 and the bottombase 20, thereby preventing the damping elements 80 from easilyseparating from the bottom base 20.

Please refer to FIG. 9A and FIG. 9B, wherein FIG. 9A is a schematicplane view illustrating the configuration of the spring sheet 70,damping elements 80, and lens holder 30 of a lens driving device inaccordance with another embodiment of the invention, and FIG. 9B is anenlarged perspective view of part F of FIG. 9A. It should be realizedthat the lower spring sheet 70 of the lens driving device 1 is used asan example for illustration in this embodiment, but the lower springsheet 70 may also be replaced by the upper spring sheet 60 (FIG. 1).

In this embodiment, the spring sheet 70 further forms a plurality of(e.g. four) openings 74A (FIG. 9B) on the inner periphery portion 74 forexposing parts of the connected surface of the lens holder 30. Moreover,the damping elements 80 are connected between the arm portions 76 of thespring sheet 70, the openings 74A and the exposed parts of the connectedsurface of the lens holder 30. Since the damping elements 80 are coupledto the arm portions 76 and to the lens holder 30, the damping elements80 can absorb and inhibit the shake generated by the arm portions 76 ofthe spring sheet 70 when the lens is moved to a fixed position to bringthe subject into focus, thereby effectively shortening the DynamicResponse Time and the focusing time.

With the design of openings 74A, the damping elements 80 may flow intothe openings 74A and then are connected between the arm portions 76 ofthe spring sheet 70, the openings 74A, and the exposed parts of theconnected surface of the lens holder 30. Thus, the damping elements 80can be accurately adhered to and positioned in the desired positions andthe bonding strength between the damping elements 80 and the lens holder30 can also be improved further. In this embodiment, the dampingelements 80 may be soft gel or any other applicable damping material.Also, the lens holder 30, preferably, may comprise resin material, sothat a better bonding strength can be achieved between the dampingelement 80 and the lens holder 30, thereby preventing the dampingelements 80 from easily separating from the lens holder 30. In someembodiments, the damping elements 80 may also be connected to the armportions 76 of the spring sheet 70 in a winding manner, so that theboding strength between the damping elements 80 and the spring sheet 70comprising metal material can also be improved further, thus preventingthe damping elements 80 from easily separating from the spring sheet 70.

Although the lens driving device 1 of the aforementioned embodiments isused as a Voice Coil Motor (VCM), the invention is not limited thereto.The lens driving device provided in some embodiments of the inventionmay also be used in a camera module with Optical Image Stabilization(OIS) technology since it can drive the camera along the X-axis and theY-axis.

While the invention has been described by way of example and in terms ofthe preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. On the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

What is claimed is:
 1. A lens driving device, comprising: a frame; alens holder movably disposed in the frame; a spring sheet having anouter periphery portion, an inner periphery portion, and at least onearm portion, wherein the outer periphery portion is connected to theframe, the inner periphery portion is connected to the lens holder, thearm portion is provided between the outer periphery portion and theinner periphery portion and directly connected to the outer peripheryportion and the inner periphery portion, so that the outer peripheryportion and the inner periphery portion are directly connected by thearm portion; and at least one damping element arranged in a spacebetween the arm portion of the spring sheet and the frame or the lensholder, the damping element being directly connected and directlyadhered to the arm portion and the frame or the lens holder.
 2. The lensdriving device as claimed in claim 1, wherein the arm portion of thespring sheet forms at least one protrusion that extends toward theframe, and the frame forms at least one recess corresponding to theprotrusion, and wherein the damping element is directly connected to theprotrusion and the recess.
 3. The lens driving device as claimed inclaim 1, wherein the arm portion of the spring sheet forms at least oneprotrusion that extends toward the lens holder, and the lens holderforms at least one recess corresponding to the protrusion, and whereinthe damping element is directly connected to the protrusion and therecess.
 4. The lens driving device as claimed in claim 1, wherein theframe forms at least one connected portion that protrudes from an innerside thereof, and the damping element is directly connected to the armportion of the spring sheet and the connected portion.
 5. The lensdriving device as claimed in claim 1, wherein the inner peripheryportion of the spring sheet forms at least one opening to which a partof a connected surface of the lens holder is exposed, and the dampingelement is directly connected to the atm portion of the spring sheet,the opening and the part of the connected surface of the lens holder. 6.The lens driving device as claimed in claim 1, wherein the dampingelement surrounds the arm portion of the spring sheet.
 7. The lensdriving device as claimed in claim 1, wherein the damping element is agel.
 8. The lens driving device as claimed in claim 1, wherein the frameand the lens holder comprise resin material.
 9. The lens driving deviceas claimed in claim 1, wherein the frame and the spring sheet arerespectively a top casing and an upper spring sheet of the lens drivingdevice.
 10. The lens driving device as claimed in claim 1, wherein theframe and the spring sheet are respectively a bottom base and a lowerspring sheet of the lens driving device.
 11. The lens driving device asclaimed in claim 1, wherein at least a part of the arm portion isprovided through a portion of the damping element.